Oval screw

ABSTRACT

An oval screw characterized by making a screw head into the shape of an oval cone which is narrowed upward and the upper part of which has been cut off, by planing the circumference of the top surface of said top-cut oval cone into a circle with a diameter corresponding to the shorter diameter of the original oval top surface, by making the longer diameter part of the original oval top surface into a slow arc slope toward the upper edge of the top-cut oval cone, and by planing off the whole upper edge of the top-cut oval cone.

United States Patent [191 1 Okada *Jan. 14, 19 75 OVAL SCREW [76] Inventor: Jujiro Okada, No. 69,

' Chodo-l-Chome, I-Iigashi-Osaka City, Japan Notice: The portion of the term of this patent subsequent to May 1, 1990, has been clisclaimed.

[22] Filed: July 24, 1972 211 Appl. No.1 274,211

[30] Foreign Application Priority Data Feb. 28, 1972 Japan 47-19703 [52] US. Cl....; 85/45, 85/9' [51] Int. Cl Fl6b 23/00 [58] Field of Search 85/45, 9

[56] References Cited UNITED STATES PATENTS 1,684,096 9/1928 Hughes 85/45 3,134,291 5/1964 Barry 85/45 3,212,392 10/1965 Wald 85/45 3,369,441 .2/1968 Kosar 85/45 3,730,048 5/1973 Okada 85/45 FOREIGN PATENTS OR APPLICATIONS 1,188,163 4/1970 Great Britain 85/45 619,623 l/l947 France 85/45 Primary Examiner-Marion Parsons, Jr. Attorney, Agent, or Firm-Wenderoth, Lind & Ponack 57 ABSTRACT An oval screw characterized by making a screw head into the shape of an oval cone which is narrowed upward and the upper part of which has been cut off, by planing the circumference of the top surface of said top-cut oval cone into a circle with a diameter corre sponding to the shorter diameter of' the original oval top surface, by making the longer diameter part of the original oval top surface into a slow arc slope toward 1 the upper edge of the top-cut oval cone, and by planing off the whole upper. edge of the top-cut oval cone.

2 Claims, 4 Drawing Figures OVAL SCREW The present invention pertains to a screw with a head shaped in a top-cut oval cone which spreads'out downwardly and which has a round top surface and also has an oval circumference with a slightly longer diameter than that of said circle. The top surface is planed into a circle and the longer diameter part of the original oval top surface is made into a slow arc slope toward the upper edge of the top-cut oval cone which is planed off.

The object of the present invention is to provide, in combination with a driver, a new and improved head construction which overcomes the objections inherent in the wood and machine screws heretofore used and possesses the following outstanding advantages, namely, presents a neater and more ornamental appear'ance than the slotted and hexagonal heads heretofore used, can be fit in a socket-type screw driver smoothly and securely, and can be driven at higher speed and tightened to the desired degree with far less efforts and attention than ordinary screws and without any danger of the head becoming disfigured or the adjacent surfaces marred, and can be manufactured by high speed production methods at lower costs than ordinary screws.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which;

FIG. 1 is a plan view of the oval screw according to the present invention.

FIG. 2 is a corresponding elevation.

FIG. 3 is a side view and FIG. 4 is a front view to show the state that the socket-type screw driver is put on the screw head.

In FIGS. v1-3,-reference numeral 1 denotes a screw body and the numeral 2 a screw head. The screw head 2 is made into a top-cut oval cone which is narrowed upward. Its top surface 3 is made into a circle with edge having been planed off.

The diameter of said circle corresponds to the shorter diameter of the top surface 3 of said top-cut oval cone, whereby the longer diameter part of the original oval top surface protrudes slightly from the circumference of the circle. Such protruded part is made into a slow arc slope 4 toward the upper edge of the top-cut oval cone.

Such being the structure of a screw of the present invention, the screw can be easily screwed in by putting a socket-type screw driver 5, which fits the slope of the top-cut oval cone, onto the screw head 2 as seen in FIG. 4 and by turning said screw driver. The slope of the top-cut oval cone offers resistance to the inner surface of the socket of the screw driver 5 thus driving the screw.

Therefore, there is no need to provide any groove on a screw surface for engaging with a screw driver as in the case of conventional screws, whereby it becomes possible to decorate the screw head by giving to its surface a polished finish or a cloisonne finish or a cut-glass looking finish.

The side of the screw head 2 is of the shape of a topcut oval cone which is narrowed upward, and yet the upper edge of the screw head 2 is planed off into an arc slope shape, due to which the screw driver 5 can be easily put on the screw head 2 and can be guided by said slope so as to engage with the screw head 2 smoothly and securely.

Now, for the purpose of protection to the top surface of the screw head 2 or to that of an object 6 to be screwed against damage, the socket of the screw driver 5 is shaped in such a way as it has gaps 7'and 8 respec- I tively between the top surface 3 of the screw head 2 and the inner surface of the socket and between the edge of the socket and the object 6 to be screwed. In this connection, it has been found that the best result is obtained when the angle a of the slope of the screw head 2 is about 6 from a perpendicular line at the lower edge of the screw head 2.

The top surface 3 of the screw head 2 is shaped into a circle with planed edge and yet the circle is succeeded by the slope at the larger diameter part of the top-cut oval cone via the slow arc slope 4, whereby the screw head 2 as a whole'gives the illusion as if it were a complete circle. Therefore, the screw head after having been applied to the object to be screwed gives a very good appearance as if it were the round head of a rivet. 7

Further, the top surface 3 of the screw head 2 is round as described above and the edge of the circle to be succeeded by the larger diameter part of the top-cut oval cone is shaped into the slow arc slope 4 and yet is planed off more than that to be succeeded by the shorter diameter part. This has such advantage that when forming an oval screw head by cold press with a shaping header, it is possible to average the flow of a screw material placed in the machine and thus to obtain uniform products.

This is to say,when the screw head to be shaped by press if of a mere oval section, the screw material pressed in the direction of the shorter diameter of the oval leaves a surplus due to a difference in capacity between the longer diameter part and the shorter diameter part, as the result of which the so-called protrusion is caused. While, in the case of the screw head in accordance with the present invention, the longer diameter part is narrowed upward with its upper edge shaped into the slow arc slope 4 and its capacity is almost the same as that of the shorter diameter part and accordingly the screw material can spread out evenly.

Thus, it is possible to obtain well-balanced and excellent products without causing any protrusion or incomplete shape due to the lack of screw material on the lower surface of the longer diameter part.

As heretofore described, the present invention has such advantage as it is possible to produce a screw being very simple in structure and yet excellent in both appearance and function.

What I claim is:

1. A screw threaded fastening element, comprising:

a threaded shank portion;

a tool engaging head having coaxially arranged upper and lowersurfaces and an inclined side portion connecting said upper and lower surfaces and adapted to engage a tool, said upper surface being smaller than said lower surface, said lower surface being fiat and connected to said threaded shank portion at an end of said shank portion, said upper surface having a circular cross section, said lower surface having an elliptical cross section having a majoraxis and a minor axis, said inclined side portion tapering upwardly from said elliptical lower surface to said circular upper surface and having a .3 v 4 varying radius of curvature, said radius of curvacal lower surface. ture being a minimum value at the intersection of 2. A screw-threaded fastening element accerding to said top surface and the plane of the major axis of claim 1, in which the mean inclination of the side porsaid elliptical lower surface and increasing to a tion of the head relative to the longitudinal axis of the maximum valve at the intersection of said top sur- 5 shank is 6.

face and the plane of the minor axis of said ellipti- 

1. A screw threaded fastening element, comprising: a threaded shank portion; a tool engaging head having coaxially arranged upper and lower surfaces and an inclined side portion connecting said upper and lower surfaces and adapted to engage a tool, said upper surface being smaller than said lower surface, said lower surface being flat and connected to said threaded shank portion at an end of said shank portion, said upper surface having a circular cross section, said lower surface having an elliptical cross section having a major axis and a minor axis, said inclined side portion tapering upwardly from said elliptical lower surface to said circular upper surface and having a varying radius of curvature, said radius of curvature being a minimum value at the intersection of said top surface and the plane of the major axis of said elliptical lower surface and increasing to a maximum valve at the intersection of said top surface and the plane of the minor axis of said elliptical lower surface.
 2. A screw-threaded fastening element according to claim 1, in which the Mean inclination of the side portion of the head relative to the longitudinal axis of the shank is 6*. 